Past experimental research has shown that violentvideogame exposure can increase aggression-related variables compared to nonviolent videogame exposure. Currently, there are two competing hypotheses to interpret these findings. The violent-content hypothesis states that violentvideogames increases aggression because the violent content increases the accessibility of aggression-related knowledge structures. The competition-only hypothesis states that violentvideogames typically have a high level of competition compared to nonviolent videogames. According to this hypothesis, the heightened level of competition increases aggression. One way to test these hypotheses is to expose participants to violent and nonviolent videogames matched on competition. Four experiments accomplished this by examining the impact of illicit violence in sportvideogames on aggression-related variables. Experiment 1 demonstrated that the illicitly violentsportvideogames contained more violence than the nonviolent same-sportvideogames, but were not significantly different on competitiveness. In the remaining experiments, participants played either a violent or nonviolent sportsvideogame. Participants then completed measures assessing aggressive cognitions (Experiment 2), aggressive affect and attitudes towards aggression in sports (Experiment 3), or aggressive behavior (Experiment 4). Exposure to violentsportsvideogames increased aggressive affect, aggressive cognition, aggressive behavior, and some positive attitudes towards aggression in sports. Because all games were competitive, these findings support the violent-content hypothesis and fail to support the competition-only hypothesis. (PsycINFO Database Record (c) 2008 APA, all rights reserved)